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linux-next/arch/x86/include/asm/apic.h
Thomas Gleixner 6f1a4891a5 x86/apic/msi: Plug non-maskable MSI affinity race 
Evan tracked down a subtle race between the update of the MSI message and
the device raising an interrupt internally on PCI devices which do not
support MSI masking. The update of the MSI message is non-atomic and
consists of either 2 or 3 sequential 32bit wide writes to the PCI config
space.

   - Write address low 32bits
   - Write address high 32bits (If supported by device)
   - Write data

When an interrupt is migrated then both address and data might change, so
the kernel attempts to mask the MSI interrupt first. But for MSI masking is
optional, so there exist devices which do not provide it. That means that
if the device raises an interrupt internally between the writes then a MSI
message is sent built from half updated state.

On x86 this can lead to spurious interrupts on the wrong interrupt
vector when the affinity setting changes both address and data. As a
consequence the device interrupt can be lost causing the device to
become stuck or malfunctioning.

Evan tried to handle that by disabling MSI accross an MSI message
update. That's not feasible because disabling MSI has issues on its own:

 If MSI is disabled the PCI device is routing an interrupt to the legacy
 INTx mechanism. The INTx delivery can be disabled, but the disablement is
 not working on all devices.

 Some devices lose interrupts when both MSI and INTx delivery are disabled.

Another way to solve this would be to enforce the allocation of the same
vector on all CPUs in the system for this kind of screwed devices. That
could be done, but it would bring back the vector space exhaustion problems
which got solved a few years ago.

Fortunately the high address (if supported by the device) is only relevant
when X2APIC is enabled which implies interrupt remapping. In the interrupt
remapping case the affinity setting is happening at the interrupt remapping
unit and the PCI MSI message is programmed only once when the PCI device is
initialized.

That makes it possible to solve it with a two step update:

  1) Target the MSI msg to the new vector on the current target CPU

  2) Target the MSI msg to the new vector on the new target CPU

In both cases writing the MSI message is only changing a single 32bit word
which prevents the issue of inconsistency.

After writing the final destination it is necessary to check whether the
device issued an interrupt while the intermediate state #1 (new vector,
current CPU) was in effect.

This is possible because the affinity change is always happening on the
current target CPU. The code runs with interrupts disabled, so the
interrupt can be detected by checking the IRR of the local APIC. If the
vector is pending in the IRR then the interrupt is retriggered on the new
target CPU by sending an IPI for the associated vector on the target CPU.

This can cause spurious interrupts on both the local and the new target
CPU.

 1) If the new vector is not in use on the local CPU and the device
    affected by the affinity change raised an interrupt during the
    transitional state (step #1 above) then interrupt entry code will
    ignore that spurious interrupt. The vector is marked so that the
    'No irq handler for vector' warning is supressed once.

 2) If the new vector is in use already on the local CPU then the IRR check
    might see an pending interrupt from the device which is using this
    vector. The IPI to the new target CPU will then invoke the handler of
    the device, which got the affinity change, even if that device did not
    issue an interrupt

 3) If the new vector is in use already on the local CPU and the device
    affected by the affinity change raised an interrupt during the
    transitional state (step #1 above) then the handler of the device which
    uses that vector on the local CPU will be invoked.

expose issues in device driver interrupt handlers which are not prepared to
handle a spurious interrupt correctly. This not a regression, it's just
exposing something which was already broken as spurious interrupts can
happen for a lot of reasons and all driver handlers need to be able to deal
with them.

Reported-by: Evan Green <evgreen@chromium.org>
Debugged-by: Evan Green <evgreen@chromium.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Evan Green <evgreen@chromium.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/87imkr4s7n.fsf@nanos.tec.linutronix.de
2020-02-01 09:31:47 +01:00

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/* SPDX-License-Identifier: GPL-2.0-only */
#ifndef _ASM_X86_APIC_H
#define _ASM_X86_APIC_H
#include <linux/cpumask.h>
#include <asm/alternative.h>
#include <asm/cpufeature.h>
#include <asm/apicdef.h>
#include <linux/atomic.h>
#include <asm/fixmap.h>
#include <asm/mpspec.h>
#include <asm/msr.h>
#include <asm/hardirq.h>
#define ARCH_APICTIMER_STOPS_ON_C3 1
/*
* Debugging macros
*/
#define APIC_QUIET 0
#define APIC_VERBOSE 1
#define APIC_DEBUG 2
/* Macros for apic_extnmi which controls external NMI masking */
#define APIC_EXTNMI_BSP 0 /* Default */
#define APIC_EXTNMI_ALL 1
#define APIC_EXTNMI_NONE 2
/*
* Define the default level of output to be very little
* This can be turned up by using apic=verbose for more
* information and apic=debug for _lots_ of information.
* apic_verbosity is defined in apic.c
*/
#define apic_printk(v, s, a...) do { \
if ((v) <= apic_verbosity) \
printk(s, ##a); \
} while (0)
#if defined(CONFIG_X86_LOCAL_APIC) && defined(CONFIG_X86_32)
extern void generic_apic_probe(void);
#else
static inline void generic_apic_probe(void)
{
}
#endif
#ifdef CONFIG_X86_LOCAL_APIC
extern int apic_verbosity;
extern int local_apic_timer_c2_ok;
extern int disable_apic;
extern unsigned int lapic_timer_period;
extern enum apic_intr_mode_id apic_intr_mode;
enum apic_intr_mode_id {
APIC_PIC,
APIC_VIRTUAL_WIRE,
APIC_VIRTUAL_WIRE_NO_CONFIG,
APIC_SYMMETRIC_IO,
APIC_SYMMETRIC_IO_NO_ROUTING
};
#ifdef CONFIG_SMP
extern void __inquire_remote_apic(int apicid);
#else /* CONFIG_SMP */
static inline void __inquire_remote_apic(int apicid)
{
}
#endif /* CONFIG_SMP */
static inline void default_inquire_remote_apic(int apicid)
{
if (apic_verbosity >= APIC_DEBUG)
__inquire_remote_apic(apicid);
}
/*
* With 82489DX we can't rely on apic feature bit
* retrieved via cpuid but still have to deal with
* such an apic chip so we assume that SMP configuration
* is found from MP table (64bit case uses ACPI mostly
* which set smp presence flag as well so we are safe
* to use this helper too).
*/
static inline bool apic_from_smp_config(void)
{
return smp_found_config && !disable_apic;
}
/*
* Basic functions accessing APICs.
*/
#ifdef CONFIG_PARAVIRT
#include <asm/paravirt.h>
#endif
extern int setup_profiling_timer(unsigned int);
static inline void native_apic_mem_write(u32 reg, u32 v)
{
volatile u32 *addr = (volatile u32 *)(APIC_BASE + reg);
alternative_io("movl %0, %P1", "xchgl %0, %P1", X86_BUG_11AP,
ASM_OUTPUT2("=r" (v), "=m" (*addr)),
ASM_OUTPUT2("0" (v), "m" (*addr)));
}
static inline u32 native_apic_mem_read(u32 reg)
{
return *((volatile u32 *)(APIC_BASE + reg));
}
extern void native_apic_wait_icr_idle(void);
extern u32 native_safe_apic_wait_icr_idle(void);
extern void native_apic_icr_write(u32 low, u32 id);
extern u64 native_apic_icr_read(void);
static inline bool apic_is_x2apic_enabled(void)
{
u64 msr;
if (rdmsrl_safe(MSR_IA32_APICBASE, &msr))
return false;
return msr & X2APIC_ENABLE;
}
extern void enable_IR_x2apic(void);
extern int get_physical_broadcast(void);
extern int lapic_get_maxlvt(void);
extern void clear_local_APIC(void);
extern void disconnect_bsp_APIC(int virt_wire_setup);
extern void disable_local_APIC(void);
extern void apic_soft_disable(void);
extern void lapic_shutdown(void);
extern void sync_Arb_IDs(void);
extern void init_bsp_APIC(void);
extern void apic_intr_mode_select(void);
extern void apic_intr_mode_init(void);
extern void init_apic_mappings(void);
void register_lapic_address(unsigned long address);
extern void setup_boot_APIC_clock(void);
extern void setup_secondary_APIC_clock(void);
extern void lapic_update_tsc_freq(void);
#ifdef CONFIG_X86_64
static inline int apic_force_enable(unsigned long addr)
{
return -1;
}
#else
extern int apic_force_enable(unsigned long addr);
#endif
extern void apic_ap_setup(void);
/*
* On 32bit this is mach-xxx local
*/
#ifdef CONFIG_X86_64
extern int apic_is_clustered_box(void);
#else
static inline int apic_is_clustered_box(void)
{
return 0;
}
#endif
extern int setup_APIC_eilvt(u8 lvt_off, u8 vector, u8 msg_type, u8 mask);
extern void lapic_assign_system_vectors(void);
extern void lapic_assign_legacy_vector(unsigned int isairq, bool replace);
extern void lapic_online(void);
extern void lapic_offline(void);
extern bool apic_needs_pit(void);
extern void apic_send_IPI_allbutself(unsigned int vector);
#else /* !CONFIG_X86_LOCAL_APIC */
static inline void lapic_shutdown(void) { }
#define local_apic_timer_c2_ok 1
static inline void init_apic_mappings(void) { }
static inline void disable_local_APIC(void) { }
# define setup_boot_APIC_clock x86_init_noop
# define setup_secondary_APIC_clock x86_init_noop
static inline void lapic_update_tsc_freq(void) { }
static inline void init_bsp_APIC(void) { }
static inline void apic_intr_mode_select(void) { }
static inline void apic_intr_mode_init(void) { }
static inline void lapic_assign_system_vectors(void) { }
static inline void lapic_assign_legacy_vector(unsigned int i, bool r) { }
static inline bool apic_needs_pit(void) { return true; }
#endif /* !CONFIG_X86_LOCAL_APIC */
#ifdef CONFIG_X86_X2APIC
/*
* Make previous memory operations globally visible before
* sending the IPI through x2apic wrmsr. We need a serializing instruction or
* mfence for this.
*/
static inline void x2apic_wrmsr_fence(void)
{
asm volatile("mfence" : : : "memory");
}
static inline void native_apic_msr_write(u32 reg, u32 v)
{
if (reg == APIC_DFR || reg == APIC_ID || reg == APIC_LDR ||
reg == APIC_LVR)
return;
wrmsr(APIC_BASE_MSR + (reg >> 4), v, 0);
}
static inline void native_apic_msr_eoi_write(u32 reg, u32 v)
{
__wrmsr(APIC_BASE_MSR + (APIC_EOI >> 4), APIC_EOI_ACK, 0);
}
static inline u32 native_apic_msr_read(u32 reg)
{
u64 msr;
if (reg == APIC_DFR)
return -1;
rdmsrl(APIC_BASE_MSR + (reg >> 4), msr);
return (u32)msr;
}
static inline void native_x2apic_wait_icr_idle(void)
{
/* no need to wait for icr idle in x2apic */
return;
}
static inline u32 native_safe_x2apic_wait_icr_idle(void)
{
/* no need to wait for icr idle in x2apic */
return 0;
}
static inline void native_x2apic_icr_write(u32 low, u32 id)
{
wrmsrl(APIC_BASE_MSR + (APIC_ICR >> 4), ((__u64) id) << 32 | low);
}
static inline u64 native_x2apic_icr_read(void)
{
unsigned long val;
rdmsrl(APIC_BASE_MSR + (APIC_ICR >> 4), val);
return val;
}
extern int x2apic_mode;
extern int x2apic_phys;
extern void __init check_x2apic(void);
extern void x2apic_setup(void);
static inline int x2apic_enabled(void)
{
return boot_cpu_has(X86_FEATURE_X2APIC) && apic_is_x2apic_enabled();
}
#define x2apic_supported() (boot_cpu_has(X86_FEATURE_X2APIC))
#else /* !CONFIG_X86_X2APIC */
static inline void check_x2apic(void) { }
static inline void x2apic_setup(void) { }
static inline int x2apic_enabled(void) { return 0; }
#define x2apic_mode (0)
#define x2apic_supported() (0)
#endif /* !CONFIG_X86_X2APIC */
struct irq_data;
/*
* Copyright 2004 James Cleverdon, IBM.
*
* Generic APIC sub-arch data struct.
*
* Hacked for x86-64 by James Cleverdon from i386 architecture code by
* Martin Bligh, Andi Kleen, James Bottomley, John Stultz, and
* James Cleverdon.
*/
struct apic {
/* Hotpath functions first */
void (*eoi_write)(u32 reg, u32 v);
void (*native_eoi_write)(u32 reg, u32 v);
void (*write)(u32 reg, u32 v);
u32 (*read)(u32 reg);
/* IPI related functions */
void (*wait_icr_idle)(void);
u32 (*safe_wait_icr_idle)(void);
void (*send_IPI)(int cpu, int vector);
void (*send_IPI_mask)(const struct cpumask *mask, int vector);
void (*send_IPI_mask_allbutself)(const struct cpumask *msk, int vec);
void (*send_IPI_allbutself)(int vector);
void (*send_IPI_all)(int vector);
void (*send_IPI_self)(int vector);
/* dest_logical is used by the IPI functions */
u32 dest_logical;
u32 disable_esr;
u32 irq_delivery_mode;
u32 irq_dest_mode;
u32 (*calc_dest_apicid)(unsigned int cpu);
/* ICR related functions */
u64 (*icr_read)(void);
void (*icr_write)(u32 low, u32 high);
/* Probe, setup and smpboot functions */
int (*probe)(void);
int (*acpi_madt_oem_check)(char *oem_id, char *oem_table_id);
int (*apic_id_valid)(u32 apicid);
int (*apic_id_registered)(void);
bool (*check_apicid_used)(physid_mask_t *map, int apicid);
void (*init_apic_ldr)(void);
void (*ioapic_phys_id_map)(physid_mask_t *phys_map, physid_mask_t *retmap);
void (*setup_apic_routing)(void);
int (*cpu_present_to_apicid)(int mps_cpu);
void (*apicid_to_cpu_present)(int phys_apicid, physid_mask_t *retmap);
int (*check_phys_apicid_present)(int phys_apicid);
int (*phys_pkg_id)(int cpuid_apic, int index_msb);
u32 (*get_apic_id)(unsigned long x);
u32 (*set_apic_id)(unsigned int id);
/* wakeup_secondary_cpu */
int (*wakeup_secondary_cpu)(int apicid, unsigned long start_eip);
void (*inquire_remote_apic)(int apicid);
#ifdef CONFIG_X86_32
/*
* Called very early during boot from get_smp_config(). It should
* return the logical apicid. x86_[bios]_cpu_to_apicid is
* initialized before this function is called.
*
* If logical apicid can't be determined that early, the function
* may return BAD_APICID. Logical apicid will be configured after
* init_apic_ldr() while bringing up CPUs. Note that NUMA affinity
* won't be applied properly during early boot in this case.
*/
int (*x86_32_early_logical_apicid)(int cpu);
#endif
char *name;
};
/*
* Pointer to the local APIC driver in use on this system (there's
* always just one such driver in use - the kernel decides via an
* early probing process which one it picks - and then sticks to it):
*/
extern struct apic *apic;
/*
* APIC drivers are probed based on how they are listed in the .apicdrivers
* section. So the order is important and enforced by the ordering
* of different apic driver files in the Makefile.
*
* For the files having two apic drivers, we use apic_drivers()
* to enforce the order with in them.
*/
#define apic_driver(sym) \
static const struct apic *__apicdrivers_##sym __used \
__aligned(sizeof(struct apic *)) \
__section(.apicdrivers) = { &sym }
#define apic_drivers(sym1, sym2) \
static struct apic *__apicdrivers_##sym1##sym2[2] __used \
__aligned(sizeof(struct apic *)) \
__section(.apicdrivers) = { &sym1, &sym2 }
extern struct apic *__apicdrivers[], *__apicdrivers_end[];
/*
* APIC functionality to boot other CPUs - only used on SMP:
*/
#ifdef CONFIG_SMP
extern int wakeup_secondary_cpu_via_nmi(int apicid, unsigned long start_eip);
extern int lapic_can_unplug_cpu(void);
#endif
#ifdef CONFIG_X86_LOCAL_APIC
static inline u32 apic_read(u32 reg)
{
return apic->read(reg);
}
static inline void apic_write(u32 reg, u32 val)
{
apic->write(reg, val);
}
static inline void apic_eoi(void)
{
apic->eoi_write(APIC_EOI, APIC_EOI_ACK);
}
static inline u64 apic_icr_read(void)
{
return apic->icr_read();
}
static inline void apic_icr_write(u32 low, u32 high)
{
apic->icr_write(low, high);
}
static inline void apic_wait_icr_idle(void)
{
apic->wait_icr_idle();
}
static inline u32 safe_apic_wait_icr_idle(void)
{
return apic->safe_wait_icr_idle();
}
extern void __init apic_set_eoi_write(void (*eoi_write)(u32 reg, u32 v));
#else /* CONFIG_X86_LOCAL_APIC */
static inline u32 apic_read(u32 reg) { return 0; }
static inline void apic_write(u32 reg, u32 val) { }
static inline void apic_eoi(void) { }
static inline u64 apic_icr_read(void) { return 0; }
static inline void apic_icr_write(u32 low, u32 high) { }
static inline void apic_wait_icr_idle(void) { }
static inline u32 safe_apic_wait_icr_idle(void) { return 0; }
static inline void apic_set_eoi_write(void (*eoi_write)(u32 reg, u32 v)) {}
#endif /* CONFIG_X86_LOCAL_APIC */
extern void apic_ack_irq(struct irq_data *data);
static inline void ack_APIC_irq(void)
{
/*
* ack_APIC_irq() actually gets compiled as a single instruction
* ... yummie.
*/
apic_eoi();
}
static inline bool lapic_vector_set_in_irr(unsigned int vector)
{
u32 irr = apic_read(APIC_IRR + (vector / 32 * 0x10));
return !!(irr & (1U << (vector % 32)));
}
static inline unsigned default_get_apic_id(unsigned long x)
{
unsigned int ver = GET_APIC_VERSION(apic_read(APIC_LVR));
if (APIC_XAPIC(ver) || boot_cpu_has(X86_FEATURE_EXTD_APICID))
return (x >> 24) & 0xFF;
else
return (x >> 24) & 0x0F;
}
/*
* Warm reset vector position:
*/
#define TRAMPOLINE_PHYS_LOW 0x467
#define TRAMPOLINE_PHYS_HIGH 0x469
extern void generic_bigsmp_probe(void);
#ifdef CONFIG_X86_LOCAL_APIC
#include <asm/smp.h>
#define APIC_DFR_VALUE (APIC_DFR_FLAT)
DECLARE_EARLY_PER_CPU_READ_MOSTLY(u16, x86_bios_cpu_apicid);
extern struct apic apic_noop;
static inline unsigned int read_apic_id(void)
{
unsigned int reg = apic_read(APIC_ID);
return apic->get_apic_id(reg);
}
extern int default_apic_id_valid(u32 apicid);
extern int default_acpi_madt_oem_check(char *, char *);
extern void default_setup_apic_routing(void);
extern u32 apic_default_calc_apicid(unsigned int cpu);
extern u32 apic_flat_calc_apicid(unsigned int cpu);
extern bool default_check_apicid_used(physid_mask_t *map, int apicid);
extern void default_ioapic_phys_id_map(physid_mask_t *phys_map, physid_mask_t *retmap);
extern int default_cpu_present_to_apicid(int mps_cpu);
extern int default_check_phys_apicid_present(int phys_apicid);
#endif /* CONFIG_X86_LOCAL_APIC */
#ifdef CONFIG_SMP
bool apic_id_is_primary_thread(unsigned int id);
void apic_smt_update(void);
#else
static inline bool apic_id_is_primary_thread(unsigned int id) { return false; }
static inline void apic_smt_update(void) { }
#endif
extern void irq_enter(void);
extern void irq_exit(void);
static inline void entering_irq(void)
{
irq_enter();
kvm_set_cpu_l1tf_flush_l1d();
}
static inline void entering_ack_irq(void)
{
entering_irq();
ack_APIC_irq();
}
static inline void ipi_entering_ack_irq(void)
{
irq_enter();
ack_APIC_irq();
kvm_set_cpu_l1tf_flush_l1d();
}
static inline void exiting_irq(void)
{
irq_exit();
}
static inline void exiting_ack_irq(void)
{
ack_APIC_irq();
irq_exit();
}
extern void ioapic_zap_locks(void);
#endif /* _ASM_X86_APIC_H */
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